Alkali treatment of agave and manila hemp fibers to produce flexible fibers



Patented Apr. 1, 1952 ALKALI TREATMENT OF QAGAVE AND MA- NILA HEMP FIBERS T PRODUCE FLEX- IBLE FIBERS Hendricus Stephanus, Haarlem, and Jacobus Rinse, Overveen,

Netherlands, assignors to Jacobus Rinse and Willem Dorst, both of Haarlem, Netherlands No Drawing. Application August 26, 1948-, Serial No. 46,372. In the Netherlands May 21, 1948 i 16 Claims.

This invention relates to a process for the im- I provement of the properties of agave fibers and manila hemp fibers wherein the same are rendered flexible without substantially diminishing their original strength. More particularly the invention relates to the treatment of such fibers in their raw state, i. e., before their separation from the bundles in which they grow with solutions of aluminum and/or zinc oxide or hydroxide in solutions of alkali metal hydroxide whereby the fibers are rendered suitable or more satisfactory for the production of rope or cloth for a number of articles of commerce, such as bags or sacks.

As produced by known processes, the raw fibers oif agave, such as sisal and manila hemp; are stiff in character and possess such slight flexibility that their employment for a number of potential industrial applications is restricted. In contrast with articles from the more flexible jute fibers,

articles from sisal fibers for example such as bags and sacks, are not satisfactory for practical use on account of their low flexibility. The raw sisal individual fibers are fairly large in diameter and the fibers are firmly held together in bundles in their natural condition.

Heretofore attempts have been made to increase the flexibility of such fibers by treating them with acids, chlorides, alkalies, soap or oils. In order to make these chemicals sufilciently active it has been necessary that they be employed at high concentrations or at high temperatures or both, but under such conditions the tensile strength of the fibers is considerably reduced and there is an appreciable loss of material in the operation.

ciently altered fibers.

It has also heretofore been proposed that various vegetable fibers including sisal and hemp fibers are chemically treated by first bleaching the same and then subjecting them to the action The treatment of the fibers with, oils, on the other hand, has resulted in insuffi-' .the tensile strength of. themfibers An object of the present invention is to produce flexible, high tensile strength fibers from agave and manila hemp fibrous masses which are admirably suited for spinning and weaving into various manufactured products b-ya process operable at low cost.

Broadly considered the present invention involves treating agave and manila hemp fibers (fibrous masses) with alkali metal hydroxide solutions containing either the oxideor hydroxide of aluminum or of zinc or both metals. Heat is generally necessary to accelerate the reaction.

The alkali concentration and temperature may be at any degree or elevation which v,doe's not destroy When high temperatures are employed, lower alkali concentrations are required.

In itspreferred mode of operation, the process involves treating the. raw fibers (fibrous masses) with any of the above-mentioned solutions in which the alkali metal hydroxide is at a relatively lowconcentration, for example less thanv 15% (calculated as Na'OHLat. an elevated temperature of from to C., the time of the treatment under these conditions being about 1 to 2 hours. In a less preferred procedure, the treatment is carried out with a more concentrated alkaline solution at an ordinary or slightly elevated temperature, in which. operation the contact of the chemicals with the reagents is rela tively long, involving several hours or a, day or more. Even superatmospheric pressures and temperatures over 100 C. can be used provided the strength of thealkaline'solution and the time of treatment are restricted such that the fibers are not weakened to any substantial degree. In general, however, the us of superatmospheric pressures and temperatures over 100 C. has no specific advantage.

The concentration of th solutions, the temperature and the time employed in the operation of the process of the present invention are correlated in such manner that thehinding or embodiment operated at higher temperatures, the concentration of the alkali hydroxide in the solution calculated as NaOH preferably amounts to from about 3 to Solutions of other alkali metals than sodium may likewise be employed.

In all operations of the process, the quantity of the metal compound preferably should not be less than an amount equivalent to 0.5% of zinc oxide or to 0.5% of aluminium oxide, calculated with reference to the total amount of the solution. The maximum qiiantity which can be used is determined by the solubility of the metal ion in the alkali metal hydroxide solution employed. The content of aluminum oxide in the solution is preferably at least 2%.

Excellent results may be obtainedby the use of alkali metal hydroxide solutions containing both zinc oxide and aluminum'oxide, for ex-" ample solutions containing from 1 to 3% of zinc oxide and 2 to 6% of aluminum oxide. alkali hydroxide solutions of this concentration are employed, the temperature of th treatment is preferably maintained higher than 60C. and

most desirably between 80 and 100 0. Under such concentrations and temperatures, requiring the treatment over a short period of from only 1 to2 hours, the loss or material is very small,

When

while the fiber at the same time retains its great ofthe overall treatment to provide fibers of best quality, the chemically treatedfibers, either before or after the mechanical processing, are treated with a flexibility imparting oil, either a mineral oil or a non-mineral oil, preferably in the form of anemulsion. The effect of the oil on thetreated fibers is surprisingly high in greatly improving the flexibility. Examples of suitable oils are light lubricating oils such as spindle oil, rapeseed oil, cottonseed oil, castor oil, fish oil. The treatment of the agave .and manila hemp fibers according to the process of the' into manufacture a cloth or the articles desired, for example ropes, bags or sacks, from the fibers and then to subject the cloth or the articles to the process hereinbefore described, including a treatment with a fiexibilizing oil.

In the following examples, set forth merely to 5 illustrate the invention, the amounts of the fibers and reagents employed are given in parts by weight. 7

Example 1 A quantity of 25 parts of henequen fibers was introduced into a sodium hydroxide solution (8%) containing 1.3% of zinc oxide, and the mass was heated for a period of one hour at 90 C. The fibrous mass obtained was then squeezed out as thoroughly as possible, Washed with water, then treated with a hydrochloric acid solution 1% again washed with water and finally dried. The resulting fibers were then subjected to mechanical processing. The fibers obtained had vention is so efi ective that it is even possible first 4 high tensile strength and during the treatment practically no loss of material occurred.

Before the obtained fibers are spun, it is preferable to treat the same with oil in accordance with known procedures, as by emersing the same in an emulsion of rapeseed oil or other conventional oil in water. After this oiling treatment, the fibers are squeezed out and dried. As a result, flexible water-repellent fibers are obtained.

Example 2 Ten parts of sisal are soaked for 16 hours at about 20 C. in a solution of 9 parts of zinc oxide and 27 parts of sodium hydroxide in 64 parts of water. Then the excess solution is re- ,moved as thoroughly aspossible by squeezing and the sisal fibers are washed successively with water, hydrochloric acid (1%) and water. Finally, the fibers are dried after which they are suitable for mechanical processing. The result ing fibers are preferably oiled as described in Example 1 before being processed.

Example 3 Twenty-one parts of raw sisal fibers are soaked for 24 hours at about 20 C. in a solution of 6 parts of aluminum hydroxide and 6 parts of zinc oxide in 200 parts of sodium hydroxide solution having a sodium hydroxide content of 13%.

After this treatment, the fibrous mass is squeezed out as thoroughly as possible and Washed'successively with Water, with a 5% aqueous solution of acetic acid and with water. Finally, the fibers are subjected to any suitable oiling treatment before being subjected to mechanical processing.

Example 4 Eight parts of manila hemp are soaked for 24 hours at about 20 C. in the solution left after the treatment of the sisal fibers employed in the process of Example 2. Thereupon the hemp mass is squeezed out, washed with water, treated with a 1% solution of hydrochloric acid, washed and dried, after which the fibers are oiledin the manner hereinbefore described.

Example 5 Forty-eight parts of manila hemp are soaked for 16 hours at 60 C. in an aqueous solution composed of 24.5 parts of sodium hydroxide, 31 parts by weight of aluminum oxide and 500 parts of water. The resulting hemp mass is then further processed by the procedure described in Example 1. a

Example '6 Twenty-five parts of Java sisal are treated for 'minutes at a temperature of C. with a 10% sodium hydroxide solution in which 3% of aluminum oxide and 1.3% of zinc oxide have been dissolved. The fibrous material obtained is then squeezed out, washed, rinsed with a 1% solution of hydrochloric acid, washed once more and finally oiled with an emulsion of mineral oil.

' Example 7 A cloth made of hene'quen fibres was soaked for about 60 minutes in the solution of Example 1 at a temperature of about 90 C. After being de- -alkalized and dried as described hereinbefore the cloth was fiexibilized ina known way in an emulsion of spindle oil in water. The cloth thus treated is very suitable for being made into sacks of a great flexibility. f

In the same way ready made sacks or bags Consisting of hencquen or sisalfibers were treated, whereby the articles obtained a high fiexibility.

The process of the present invention has the outstanding advantage that the treatment conditions may readily be so chosen that the undesired binding components of the fibrous mass, such as pectins and lignins, can be dissolved out without the fibers themselves being chemically attacked to any substantial degree. As a result, the substances cross-linking or binding the fibers together disappear and the fibers retain substantially their original length and tensile strength. The process also has the advantage that the loss of material ordinarily is very small.

The process of the present invention also has the advantage that it is not necessary to prebleach the fibers. Hence the cost and detrimental effects of the bleaching operation are avoided.

The herein before disclosed oil treatment has a surprisingly beneficial effect in improving the flexibility of the fibers. The raw fibers are practically not improved at all by the oil treatment and hence the novel treatment step of the present invention alters the fibers physically or chemically in such manner that the oil treatment can become efiective.

It should be understood that the present invention is not limited, except as herein indicated, to the specific compounds and conditions of treatment disclosed, but that it extends to all equivalents which will occur to those skilled in the art upon consideration of the tenor of the specification and the scope of the claims appended hereto.

We claim:

1. A process for the production of strong, fiexible, cellulose fibers from raw agave and manila hemp fibrous masses the individual fibers of which are bound together with lignin and other natural binding substances which comprises, contacting the said fibrous masses with an aqueous alkali metal hydroxide solution of about 3-15% concentration (calculated as sodium hydroxide) containing dissolved therein at least 0.5% (calculated as oxide) of at least one compound of the group consisting of aluminum and zinc oxides and hydroxides until the said binding substances are substantially dissolved out while leaving the cellulose fibers substantially free from attack, and removing the solution containing the dissolved binding substances from the fibers, whereby the strong, flexible, cellulose fibers are obtained.

2. A process for the production of strong, flexible, cellulose fibers from raw agave and manila hemp fibrous masses the individual fibers of which are bound together with lignin and other natural binding substances which comprises, contacting the said fibrous masses with an aqueous alkali metal hydroxide solution of about 13-15% concentration (calculated as sodium hydroxide) containing dissolved therein at least 0.5% (calculated as oxide) of at least one compound of the group consisting of aluminum and zinc oxides and hydroxides until the said binding substances are substantially dissolved out while leaving the cellulose fibers substantially free from attack, and removing the solution containing the dissolved binding substances from the fibers, drying the fibers and subjecting the same to mechanical processing whereby strong, flexible, cellulose fibers in condition for spinning are obtained.

3. A process for the production of strong, flexible, cellulose fibers from raw agave and manila hemp fibrous masses the individual fibers of which are bound together with lignin and other natural binding substances which comprises, contacting thesaid fibrous masses with an aqueous alkali metal hydroxide solution of about 345% concentration (calculated as sodium hydroxide) containing dissolved therein at least 0.5% (calculated as oxide) of at least one compound of the group consisting of aluminum and zinc oxides and hydroxides until the said binding substances are substantially dissolved out while leaving the cellulose fibers substantially free from attack, and removing the solution containing the dissolved binding substances from the fibers, drying the fibers and applying thereto a flexibility iniparting oil whereby strong, water-repellent fibers of increased flexibility are obtained.

t. A process for the removal of lignins and other natural substances binding the cellulose fibers together in raw agave and manila hemp fibrous masses whereby strong, flexible fibers are obtained which comprises, submerging said raw fibrous masses in an aqueous alkali metal hydroxide solution of about 345% concentration (calculated as sodium hydroxide) containing dissolved therein at least 0.5% (calculated as oxide) of at least one compound of the group consisting of aluminum and zinc oxides and hydroxides and heating the solution containing the fibrous masses until the said binding substances are substantially dissolved out while leaving the cellulose fibers substantially free from attack, and removing the solution containing the dissolved binding substances from the fibers, whereby strong, flexible, cellulose fibers are obtained.

. 5. A process for the production of strong, flexible, cellulose fibers from raw agave and manila hemp fibrous masses the individual fibers of which are bound together with lignin and other natural binding substances which comprises, consetting the said fibrous masses with an aqueous sodium hydroxide solution of 3-10% concentration containing dissolved therein at least 0.5% (calculated as oxide) of at leastone compound of the group consisting of aluminum and zinc oxides and hydroxides until the said binding substances are substantially dissolved out while leaving the cellulose fibers substantially free from attack, and removing the solution containing the dissolved binding substances from the fibers, whereby strong, flexible, cellulose fibers are obtained.

6. A process for the production of strong, flexible cellulose fibers from raw agave and manila hemp fibrous masses the individual fibers of which are bound together with lignin and other natural binding substances which comprises, contacting the said fibrous masses with an aqueous alkali metal hydroxide solution of about 345% concentration (calculated as sodium hydroxide) containing dissolved therein at least (calculated as oxide of at least one compound of the group consisting of aluminum and zinc oxides and hydroxides until the said binding substances are substantially dissolved out while leaving the cellulose fibers substantially free from attack. and removing the solution containing the dissolved binding substances from the fibers, drying the fibers, applying thereto a flexibility-imparting oil, and subjecting the fibers to mechanical processing whereby strong, flexible, cellulose fibers in condition for springing are obtained.

'7. A process for the production of strong, flexible, cellulose fibers from agave and manila hemp fibrous masses the individual fibers of which are bound together with lignin and other natural. binding substances which comprises, contacting the said fibrous masses with an aqueous alkali metal hydroxide solution of about 13-15% concentration (calculated as sodium hydroxide) containing dissolved therein at least 0.5% of zinc oxide until the said binding substances are substantially dissolved out while leaving the cellulose fibers substantially free from attack, and removing the solution containing the dissolved binding substances from the fibers, whereby strong, flexible, cellulose fibers are obtained.

8. A process for the production of strong,

flexible, cellulose fibers from agave and manila hemp fibrous masses the individual fibers of which are bound together with lignin and other natural binding substances which comprises, contacting the said fibrous masses with an aqueous alkali metal hydroxide solution of about 345% concentration (calculated as sodium hydroxide) containing dissolved therein at least aluminum oxide until the said binding substances are substantially dissolved out while leaving the cellulose fibers substantially free from attack, and removing the solution containing the dissolved binding substances from the fibers, whereby strong, flexible, cellulose fibers are obtained. V

9. A process for the production of strong, flexible, cellulose fibers from agave and manila hemp fibrous masses the individual fibers of which are bound together with lignin and other naturall binding substances which comprises, contacting the said fibrous masses with an aqueous alkali metal hydroxide solution of about 13-15% concentration (calculated as sodium hydroxide) containing dissolved therein at least which are bound together with lignin and other natural binding substances which comprises contacting the'said fibrous masses at a temperature in excess of about 60 C. with an aqueous alkali metal hydroxide solution of about 3-15% concentration (calculated as sodium hydroxide) culated as oxide) of at least one compound or" the' group' consisting of aluminum. and zinc oxides and hydroxides until the said binding substances are substantialy dissolved out while solution containing the dissolved binding substances from the fibers, whereby strong, flexible, cellulose fibers are obtained.

12. A process for the production of strong, flexible, cellulose fibers from agave and manila hemp fibrous masses the individual fibers of which are bound together with lignin and other natural binding substances which comprises, contacting the said fibrous masses at a temperature of 60- 100 C. with an aqueous sodium hydroxide solution of about 3 to 10% concentration containing dissolved therein atleast 0.5% of zinc oxide until the said binding substances are substantially dissolved out while leaving the cellulose fibers substantially free from attack, and removing the solution containing the dissolved binding substances from the fibers, whereby strong, flexible, cellulose fibers are obtained.

13. A process for the production of strong, flexible, cellulose fibers from agave and manila hemp fibrous masses the individual fibers of which are bound together with lignin and other natural binding substances which comprises, contacting the said fibrous masses at a temperature of Gil-100 C. with an aqueous sodium hydroxide solution of about 3 to 10% concentration containing dissolved therein at least 0.5% (calculated as oxide) of at least one compound of the group consisting of aluminum and zinc oxides and hydroxides until the said binding substances are substantially dissolved out while leaving the cellulose fibers substantially free from attack,

.50 containing dissolved therein at least 0.5% (calleaving the cellulose fibers substantially free least one compound of the group consisting of aluminum and zinc oxides and hydroxides until the said binding substances are substantially dissolved out while leaving the cellulose fibers substantially free from attack, and removing the removing the solution containing the dissolved substances from the fibers, drying the fibers and applying thereto a flexibility-imparting oil whereby strong, water-repellent fibers of increased flexibility are obtained.

14. A process for the production of strong, flexible, cellulose fibers from agave and manila hemp fibrous masses the individual fibers of which are bound together with lignin and other natural binding substances which comprises, contacting the said fibrous masses with an aqueous sodium hydroxide solution of about 3 to 10% concentration containing dissolved therein 2-6% aluminum oxide and 1-3% zinc oxide until the said binding substances are substantially dissolved out while leaving the cellulose fibers substantially free from attack, and removing the solution containing the dissolved binding substances from the fibers, whereby strong, flexible,

cellulose fibers are obtained.

15. A process for the production of strong, flexible, cellulose fibers from agave and manila hemp fibrous masses the individual fibers of which are bound together with lignin and other natural binding substances which comprises, contacting the said fibrous masses with an aqueous sodium hydroxide solution of about 10% concentration containing dissolved therein about 3% aluminum oxide and about 1.3% zinc oxide until the said binding substances are substantially dissolved out while leaving the cellulose fibers substantially free from attack, and removing the solution containing the dissolved binding substances from the fibers, whereby the strong, flexible, cellulos fibers are obtained. I

16. A process for the production of strong,

flexible, cellulose fibers from agave and manila hemp fibrous masses the individual fibers of which are bound, together with lignin and other natural binding substances which comprises, contacting the said fibrous masses at a temperature of 60-100 C. with an aqueous alkali metal hydroxide solution of about 3 to 10% concentrasubstances from the fibers, whereby strong, fiex- 10 ible, cellulose fibers are obtained.

HENDRICUS STEPHANUS. JACOBUS RINSE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Number Name Date Worden Oct. 13, 1936 Edelstein June 8, 1948 FOREIGN PATENTS Country Date Great Britain Dec. 17, 1890 Great Britain Jan. 12, 1940 Great Britain Apr. 19, 1917 Great Britain Aug. 29, 1928 

1. A PROCESS FOR THE PRODUCTION OF STRONG, FLEXIBLE, CELLULOSE FIBERS FROM RAW AGAVE AND MANILA HEMP FIBROUS MASSES THE INDIVIDUAL FIBERS OF WHICH ARE BOUND TOGETHER WITH LIGNIN AND OTHER NATURAL BINDING SUBSTANCES WHICH COMPRISES, CONTACTING THE SAID FIBROUS MASSES WITH AN AQUEOUS ALKALI METAL HYDROXIDE SOLUTION OF ABOUT 3-15% CONCENTRATION (CALCULATED AS SODIUM HYDROXIDE) CONTAINING DISSOLVED THEREIN AT LEAST 0.5% (CALCULATED AS OXIDE) OF AT LEAST ONE COMPOUND OF THE GROUP CONSISTING OF ALUMINUM AND ZINC OXIDES AND HYDROXIDES UNTIL THE SAID BINDING SUBSTANCES ARE SUBSTANTIALLY DISSOLVED OUT WHILE LEAVING THE CELLULOSE FIBERS SUBSTANTIALLY FREE FROM ATTACK, AND REMOVING THE SOLUTION CONTAINING THE DISSOLVED BINDING SUBSTANCES FROM THE FIBERS, WHEREBY THE STRONG, FLEXIBLE, CELLULOSE FIBERS ARE OBTAINED. 